Cushioning mechanism



Oct. 1, 1940- R7 HQB5QN V I 2,216,473

CUSHIONING MECHANISM I Filed May 21, 1937 2 Sheets-Shae; l

INVENTOR Roy C. Hobson BY C(MW- ATTORNEY Oct. 1, 1940. a g, HQBSQN 2,216,473

CUSHIONING MECHANISII Filed May 21, 1957 '2 Sheets-ShetZ INVENTOR ATTORN EY Patented Oct. "1, 1940 UNITED STATES PATENT OFFICE CUSHIONING MECHANISM Roy 0. Hobson, Cleveland Heights, Ohio, assignor to National Malleable and Steel Castings Company, Cleveland, Ohio, a corporation of Ohio Application May 21, 1937, Serial No. 143,918

18 Claims.

This invention relates to friction cushioning mechanism for railway car trucks, though it is applicable for use on other equipment where cushioning is desired. Cushioning mechanism 5 embodying my invention may be substituted for one or more of the coil springs of the usual spring support for car trucksto effectively damp out the oscillations of the bolster set up by travel over rough track, rail joints, etc.

My invention pertains more particularly to cushioning mechanism wherein the entire load on the mechanism is transmitted to friction shoes through a resilient block of material such as rubber to force the shoes into frictional engage- 25 Figure 3 is a plan view partly in section, taken on line 3-3 of Fig. 4, showing a modified form of construction.

Figure 4 is a central longitudinal section of the cushioning mechanism shown in Fig. 3.

Figure 5 is a plan view partly in section, taken on line 55 of Fig. 6, showing another modified form of construction; and

Figure 6 is a central longitudinal sectional view of the cushioning mechanism shown in Fig. 5.

casing l having an inner friction surface I l and a laterally extending annular flange l2 at one end thereof. Cooperating with the friction surface H of the casing ID are the oppositely disposed segmental friction shoes l3 and I4 having flange portions l5 and [6, respectively. Surrounding the casing and shoes is a spring I! interposed between the annular flange 12 of the casing l0 and the flange portions l5 and I6 of the friction shoes. Spring I1 is held under initial compression by means of rod I8 which normally bears against the upper end of slots 19 in casing l0 and against the bottom surfaces of the apertures 20 and 2| in the friction shoes 13 and I4, respectively. Rod I8 is prevented from sliding out of casing H) by the cotter pins 22, 22 and in the operation of the unit moves vertically in slot I9. Carried in the pocket formed by the friction shoes and supported by the inwardly disposed flanges 25 and 26 thereof is a rubber block In Figs. 1 and 2 there is shown a cylindrical 21 adapted to transmit a lateral force to the shoes when subjected to a compressive load, causing the shoes to bear against the friction surface ll of the casing l0.

It will be observed that some clearance is present between the opposed edges of the shoes and of flanges 25 and 26. In order to prevent the rubber from being forced into these spaces, a split sleeve 28 is positioned between the rubber block and the shoes and a circular plate 29 is interposed between the rubber and flanges 25 and 26. The split in the sleeve is placed toone side of the spaces between the shoes, as shown in 28, so that these spaces are bridged by solid .metal.

Between the friction shoes and resting on block 21 is the follower 30, having a curved bearing surface 3| engaging the block, and an annular flange 32 adapted to contact the under side of a bolster. In this arrangement the rubber may not be under any initial compression other than that necessary tohold the shoes in position and in contact with the friction casing.

In the operation of the device, assuming a load applied to follower30, the first action is to compress the rubber block 21 until the applied load reaches an amount sufficient to equal the resist- .ance of coil spring l1, plus the static friction developed between the shoes and casing. If at this point it is assumed that no more friction is developed, then a further increase in load will cause the shoes to move relative to the casing. However, since successive increases in load result in more and morefriction, no movement of the shoes will take place until the rate of increase in load is greater than the rate of increase of the 35 friction developed. When this occurs, the shoes will move relative to the friction casing, and friction will be developed between the friction surfaces. The main function of the rubber block in the operation of the-'unit is to transmit a lat- 4o eral or radial force to the shoes upon the application of a vertical load to the rubber block through the follower.-

I have found that the capacity of my cushion ing mechanism can be varied by changing the shape of surface 3| of follower 30. As the radius of curvature of surface 3| is shortened the frictional capacity of the mechanism is increased and, on the other hand, as surface 3| is flattened out less frictional capacity is obtained. Therefore, by forming the surface engaging the rubber means curved as shown at 3| in Fig. 2, or flat as in the modifications about to be discussed, or by making said surface more or less curved than that shown in Fig. 2 the frictional capacity of the device may be varied over a wide range. Furthermore, the frictional capacity may be varied by changing the thickness of the rubber block. As the thickness is increased the friction is increased, since the rubber is easier to compress, thus causing a greater proportion of the force applied to follower 30 to be transferred radially to the shoes. Alternatively the friction may be decreased by decreasing the thickness of the rubber block.

In Figs. 3 and 4 is shown a modified form of construction in which the friction shoes 35 and face of'the' spring as they are urged together by I6 cooperate with the inner friction surface 31 of helical spring 38. In the pocket formed by the friction shoes is a rubber block 39 which is surrounded by a split sleeve 40. Interposed be tween the inwardly disposed flanges 4| and 42 and the block is the circular plate 43. At one end of the unit is a follower 44 having a cylindrical portion 45 extending into the spring and an annular flange 46 contacting an end of the spring. At the other end of the spring is a follower having an annular flange 41 spaced from the spring and shoes, and a cylindrical portion 48 extending into the spring. A flat thrust surface 49 at the end of portion 48 contacts block 39 and is adapted to transmit loads to said block. Bolt 50 passing through the center of the unit is provided to hold the component parts together, and by means of nut ii the initial compression of the unit may be varied as desired.

The principle of operation of the unit is the same as that of the preceding one, the rubber transmitting a lateral force to the friction shoes, producing a frictional force between the shoes and the friction surface of the spring which acts to resist the compression of the spring during the application of a load, and which reverses direction to oppose the reaction of the spring when the load is released. In this modification the thrust surface 49 is shown as being flat, however it is to be understood that it may also be curved similar to surface 3| shown in Fig. 2.

In Figs. 5 and 6 is shown another modified form of construction in which the spring is not under initial compression. The rubber block 58 is held under initial compression by the thrust surface 51 of follower it, which follower is provided with projections 59 and 00 adapted to flt into apertures ii and 62, respectively, of the shoes 63 and 64. These apertures are shown. longer than the vertical extent of projections 59 and so as to provide for compression of the rubber by follower The block may be surrounded by a split sleeve 65, and a circular plate 66 may be interposed between the block and the inwardly disposed flanges i1 and 88 of the friction shoes as in the previous constructions. In the assembling of the unit, the; shoes, follower, and' block are first assembled and then the spring is pressed over the shoes, causing the rubber to be compressed and hold the follower flrmly in position with its shoulders 59 and GI bearing against the bottoms of apertures.

SI and 62, respectively.

' In the operation of the unit the coils of the spring not contacting the friction shoes are free to act with load variations applied to the unit whilecompression and reaction of theunit as a whole is resisted by the friction developed-be *tween the friction shoes and'the friction sur-' the rubber block. In this modification also the thrust surface 51 of the follower is shown as being flat, but it is to be understood that it may also be curved, as the thrust surface 3| in Fig. 2.

The terms and expressions which I have employed are used as terms of description and not of limitation, and I have no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described or portions thereof, but recognize that various modifications: are possible within the scope of the invention claimed.

What I claim is:

1. In a cushioning mechanism a follower member, resilient means comprising a spring member surrounding said follower member, friction shoes having portionswithin and portions in engagement with an end of said spring member, one of said members having friction surfaces engaged by said shoes, resilient means comprising rubber between said shoes adapted to transmit the entire load applied to said mechanism to said shoes to urge thelatter into closer frictional engagement with said surfaces, one of said resilient means being so constructed and arranged as to provide a limited amount of free resilient movement thereof unopposed by the friction developed betweenthe friction shoes and the one of said members in engagement therewith.

2. A cushioning mechanism comprising a friction casing having an inner friction surface, friction shoes adapted to engage said surface each having an outwardly extending flange at one end and an inwardly disposed flange intermediate the ends thereof projecting toward and extending substantially to the corresponding flange'on an opposite shoe, spring means engaging said casing and said outwardly extending flanges, rubber means between said shoes and supported on said inwardly disposed flanges, and pressure transmitting means engaging said rubber means adapted to compress said rubber means adapted to resist relative longitudinal move ment between, said shoes and casing. pressure transmitting means projecting outwardly of said shoes, and rubber means between said shoes and said pressure transmitting means and engaging said shelves adapted to urge said shoes laterally toward said casing upon the application of a load to said pressure transmitting means.

4. In a cushioning mechanism a follower, a spring engaging said follower at one end thereof and having 'an'inner friction surface, friction shoes engaging said surfaceeach having a" flange engaging the opposite end of the spring from said follower, and rubber means engaging said shoes adapted to transmit the load ap'-' said surface.

5. In a cushioning mechanism a follower, 'a

spring engaging said follower at one end thereof and having an inner friction surface, friction shoes engaging said surface each having a flange engaging the opposite end of the spring from said follower, a member having a flange extending in overlapping relation to but spaced shoes and member adapted to transmit the load from said shoes, and rubber means between said a applied to said mechanism radially outward to urge said shoes into closer frictional engagement with said surface.

6. In a cushioning mechanism a helical spring having an inner friction surface, friction shoes engaging said surface, each shoe having a lat:-

-erally extending flange engaging an end of said spring and a recess adjacent said flange, a. follower having projections extending into said recesses for maintaining said shoes and follower in assembled relation, and rubber means between said shoes and follower adapted to transmit pressure applied to said follower radially outward to force said shoes into engagement with said surface.

7. In a cushioning mechanism a follower member, a spring member surrounding said follower member, spaced friction shoes within said spring member, one of said members having friction surfaces engaged by saidshoes, rubber means between said shoes adapted to transmit pressure thereto, and expandable means between said rubber means and shoes adapted to prevent said rubber means from entering the spaces between said shoes.

8. In a cushioning mechanism a follower member, a spring member surrounding said follower member, spaced friction shoes within said spring member, one of said members having friction surfaces engaged by said shoes, rubber means between said shoes adapted totransmit pressure thereto, and an expandable sleeve between said rubber means and shoes adapted to prevent said rubber means from entering the spaces between said shoes.

9. A cushioning mechanism comprising a friction casing having an inner friction surface, spaced friction shoes engaging said surface, each shoe having an inwardly disposed flange, spring means engaging said casing and shoes, rubber means between said shoes and supported by said flanges, pressure transmitting means engaging said rubber means, and means between said rubber means and said flanges bridging the spaces between the flanges on adjacent shoes.

10. In a cushioning mechanism a follower member, a spring member surrounding said follower member, spaced friction shoes within said spring member each of said shoes having a flange engaging said spring means and an inwardly projecting flange, one of said members having friction surfaces engaged by said shoes, rubber means supported bysaid flanges adapted to transmit load to said shoes, and means between said rubber means and flanges bridging the spaces between the flanges on adjacent shoes.

11. In a cushioning mechanism, friction shoes having friction surfaces on the outer side thereof, means surrounding said shoes including a spring, said means having friction surfaces adapted to be engaged by said shoes, a follower within said shoes projecting beyond and spaced from said spring, and rubber means between said follower and shoes adapted to transmit forces radially outwardly to urge said shoes into closer frictional engagement with the friction surfaces on said means, said follower applying forces to said rubber means through curved engaging means.

12. In a cushioning device, in combination, a tubular member, segmental shoes each having a stem portion extending within said tubular member, spring means acting between said tubular member and shoes for urging them apart, a compressed rubber cylinder positioned between said shoe stems for urging them radially of the device into bearingrelation with said tubular member, a plunger movable longitudinally of the device having a portion extending outwardly of said shoes and arranged to energize said cylinder when a load is applied to said device.

13. In a cushioning device, a combination, a tubular member, segmental shoes each having a stem portion extending within said tubular member, spring means acting between said tubular member and shoes for urging them apart, a rubber cylinder positioned between said shoe stems and normally urging them radially of the device into bearing relation with said tubular member, a plunger positioned adjacent one end of said device movable longitudinally thereof and arranged to' energize said cylinder when a load is applied to said device, said plunger having a portion thereof extending beyond the corresponding end of said device.

14. In a cushioning device, in combination, a tubular member, shoes movable longitudinally of the device and extending into said tubular member, spring means acting between said tubular member and shoes, a compressed resilient means positioned axially of the device for urging said shoes radially into bearing engagement with said tubular member, means adjacent one end of said shoes, a plunger positioned adjacent the other end of said shoes having a portion thereof extending outwardly of said shoes, said plunger being adapted to urge said compressed resilient means against said shoe means to develop additional compressive forces in said compressed resilient means'when a load is applied to said device.

15. A cushioning mechanism comprising a friction casing having an inner friction surface, spaced friction shoes engaging said surface, each shoe having an inwardly disposed flange, spring means acting between said casing and shoes, rubber means between said shoes and supported by said flanges, pressure transmitting means engageable with said rubber means, and means between said rubber means and said flanges bridging the spaces between the flanges on adjacent shoes.

16. In a cushioning mechanism a follower member, a spring member surrounding said follower member, spaced friction shoes within said spring member each of said shoes having a flange actof, a friction casing surrounding said shoes and 6 in frictional engagement therewith, spring means surrounding said casing and positioned between said casing and shoes, each of said shoes having an inwardly projecting flange, rubber means supported by said flanges adapted to transmit load to said shoes, and pressure transmitting means extending into said casing adapted to engage said rubber means.

18. In a cushioning device, in combination, a tubular member, shoes movable longitudinally of .the device and extending into said tubular member, spring means surrounding said tubular member and acting between said tubular member and shoes, a compressible cylinder positioned between said shoes for urging them radially into engagement with said tubular member, a plunger .positioned' adjacent one end of said shoes and having a portion thereof extending outwardly of said shoes, said plunger engaging said cylinder and being adapted to move inwardly of the defvi c'e during a compressive movement thereof to of the device.

ROY C. HOBSON. 

